Efficient long-term laser excitation of a collimated beam of potassium atoms on the D2 line

Abstract.

With the aim to provide a reliable scheme for efficient laser excitation of the potassium D2 line over long periods of time, we have developed a robust stabilization of a single mode laser of frequency f ₀ = (f ₁₂ + f ₂₃)/2 onto a crossover peak in the saturation spectrum of the ³⁹K(D2) line (4s ²S $_{1/2}, F \to 4p ^{2}$P $_{3/2}, F^{\prime} )$. The two hyperfine transitions $F = 1\to F^{\prime} = 2$ (frequency f ₁₂) and $F = 2\to F^{\prime} = 3$ (frequency f ₂₃) are simultaneously excited by the first order sidebands $f_{\pm} = f_{0}\pm f_{EOM}$ of the laser beam (f ₀), generated by its electro-optical modulation at the frequency f _EOM = (f ₁₂-f ₂₃)/2. In this way stable excitation of the two transitions on their proper frequencies is achieved and hyperfine pumping compensated.